A worm's eye view

I don't know what it really costs to drive a car from London to northern Lapland and back, but I know what I have just spent on petrol for that journey: £707.15. I suppose I should add on about £250 in ferry costs, another £60 in bridge tolls and some unknown amount in depreciation. Let's call it a round thousand.

It does seem an enormous sum. For one person to drive a car to the high North is not only a great deal slower than flying, it is more expensive even than a full business class return, and something between five and ten times as much as a budget flight would be. But is a thousand pounds what that journey ought to cost, if we are to avert catastrophic climate change?

Looking into this question seriously, I had my first shock. Travelling alone in the car seems to be almost the most selfish decision I could have made from the planet's point of view. I warmed the earth more by driving than I would have done by flying. There are various emissions calculators available on the web. Both the American EPA and the British National Energy Foundation reckon that 5,000 miles by car add more carbon to the atmosphere than 5,000 passenger miles. My exhaust gases added about 500 kilos or half a ton of carbon to the atmosphere; if I had flown, the figure would have been about 400 kilos. These are rough estimates, and if the emissions of the ferry to Holland are added in, my decision to drive would look even more environmentally unfriendly.

The crucial point in this calculation is that I drove alone. With two or more people in the car, the balance of environmental advantage is completely reversed. What makes commercial flight relatively friendly to the earth is exactly the crowding that makes it so unattractive on a human level.

But these figures may themselves be misleading. The carbon dioxide I added as a driver was released very close to the ground. The carbon dioxide released by planes may, weight for weight, be two or three times more damaging because it is released at high altitudes where it contributes more immediately to the greenhouse effect. The airlines find these calculations unconvincing, and will certainly fight against any attempt to weight, with taxes, the cost of air travel, as the Swedes are proposing to do.

The Swedish government is waiting for approval from the EU for a tax that would apply to almost all flights from Swedish airports. It's not a large tax - it's £7.50 for an internal flight. But it is, so far as I know, the first tax in the world entirely justified as a means of discouraging people from flying, for the environment's sake. This has produced entirely predictable outrage among the companies and airports affected.

Ryanair has announced that its whole operation in Sweden is threatened by the levy. It is cutting back on several routes and closing entirely its operations in Vasteras. Now it may be that these routes never were very profitable. People unfamiliar with Scandinavian geography may have not have expected from Ryanair's description of the airport as "Stockholm Vasteras" that it would turn out to be 70 miles from Stockholm, convenient though it is for visits to central Norway.

But underneath the bluster and showboating there is a very serious point. Most of the cost of my journey by car was actually in taxes: petrol for cars is heavily taxed everywhere in western Europe, while petrol for aviation fuel is nowhere taxed at all. But if, or rather when, the price of oil rises to point where aviation fuel becomes as expensive as car petrol is now, the price of air travel must rise to the point where no one will do it for fun. From a strictly environmental point of view, that is obviously right. The only people who might be travelling carbon-efficiently by air are those who would always travel alone - in other words, business travellers. Everyone else should take their holidays in shared cars, or on trains.

The end of cheap air travel would - will - most affect the world in terms of freight charges. Since most of the stuff we buy today is made on the other side of the world, it will be more expensive. But the freedom and fun that tourism by air have brought us should not be underestimated. Losing it, or finding that most people can't afford it, will be a real impoverishment; but I think our children will have been very lucky if that turns out to be the worst consequence of global warming.